Chemokines, also known as chemotactic cytokines, are a group of small molecular-weight proteins that are released by a wide variety of cells and have a variety of biological activities. Chemokines attract various types of cells of the immune system, such as macrophages, T cells, eosinophils, basophils and neutrophils, and cause them to migrate from the blood to various lymphoid and none-lymphoid tissues. They mediate infiltration of inflammatory cells to sites of inflammation, and are responsible for the initiation and perpetuation of many inflammation diseases (reviewed in Schall, Cytokine, 3:165-183 (1991), Schall et al., Curr. Opin. Inmunol., 6:865-873 (1994)).
In addition to stimulating chemotaxis, chemokines can induce other changes in responsive cells, including changes in cell shape, granule exocytosis, integrin up-regulation, formation of bioactive lipids (e.g., leukotrienes), respiratory burst associated with leukocyte activation, cell proliferation, resistance to induction of apoptosis and angiogenesis. Thus, chemokines are early triggers of the inflammatory response, causing inflammatory mediator release, chemotaxis and extravasation to sites of infection or inflammation. They are also stimulators of a multitude of cellular processes that bear important physiological functions as well as pathological consequences.
Chemokines exert their effects by activating chemokine receptors expressed by responsive cells. Chemokine receptors are a class of G-protein coupled receptors, also known as seven-transmembrane receptors, found on the surface of a wide variety of cell types such as leukocytes, endothelial cells, smooth muscle cells and tumor cells.
Chemokines and chemokine receptors are expressed by intrinsic renal cells and infiltrating cells during renal inflammation (Segerer et al., J. Am. Soc. Nephrol., 11:152-76 (2000); Morii et al., J. Diabetes Complications, 17:11-5 (2003); Lloyd et al. J. Exp. Med., 185:1371-80 (1997); Gonzalez-Cuadrado et al. Clin. Exp. Immuno. 106:518-22 (1996); Eddy & Giachelli, Kidney Int., 47:1546-57 (1995); Diamond et al., Am. J. Physiol., 266:F926-33 (1994)). In humans, CCR2 and ligand MCP-1 are among the proteins expressed in renal fibrosis, and are correlated with the extent of macrophage infiltration into the interstitium (Yang et al., Zhonghua Yi Xue Za Zhi, 81:73-7 (2001); Stephan et al., J. Urol., 167:1497-502 (2002); Amann et al., Diabetes Care, 26:2421-5 (2003); Dai et al., Chin. Med. J. (Engl), 114:864-8 (2001)). In animal models of renal fibrosis, blockade of CCR2 or MCP-1 leads to a marked reduction in severity of renal inflammation (Kitagawa et al., Am. J. Pathol., 165:237-46 (2004); Wada et al., Am. J. Pathol., 165:237-46 (2004); Shimizu et al., J. Am. Soc. Nephrol., 14:1496-505 (2003)).
Additionally CCR2 plays a role in the development of polycystic kidney disease (PKD). The pathology of ADPKD is characterized by renal cysts that arise from tubular epithelial cells and enlarge continuously over the patient's lifetime. The expanding cysts are accompanied by the presence of a large number of infiltrating macrophages which are recruited to the kidney in response to injury. Thus, inhibition of immune recruitment to the kidney constitutes a therapeutic strategy for PKD (J Am Soc Nephrol. 2011 October; 22(10): 1809-14.)
Rheumatoid arthritis is a chronic disease of the joints characterized by synovial inflammation that leads to the destruction of cartilage and bone. Although the underlying causes of the disease are unknown, it is believed that macrophages and Th-1 type T cells play a key role in the initiation and perpetuation of the chronic inflammatory process (Vervoordeldonk et al., Curr. Rheumatol. Rep., 4:208-17 (2002)).
MCP-1 is among the several chemokines, including MIP-1α and IL-8, identified in rheumatoid synovium (Villiger et al., J. Immunol., 149:722-7 (1992); Scaife et al., Rheumatology (Oxford), 43:1346-52 (2004); Shadidi et al., Scand. J. Immunol., 57:192-8 (2003); Taylor et al., Arthritis Rheum., 43:38-47 (2000); Tucci et al., Biomed Sci. Instrum., 34:169-74 (1997)). Chemokine receptors CCR1, CCR2. CCR3 and CCR5 are up-regulated in the joints from arthritic mice (Plater-Zyberk et al., Immunol. Lett., 57:117-20 (1997). Blockade of MCP-1 activity using a CCR2 antagonist or an antibody against MCP-1 have been shown efficacious in reducing joint inflammation in experimental models of rheumatoid arthritis (Gong et al., J. Exp. Med., 186:131-7 (1997); Ogata et al., J. Pathol., 182:106-14 (1997)).
Chemokine receptor-mediated infiltration of macrophages in the fat tissues may also contribute to the complications arising from obesity, a condition resulting from excessive storage of fat in the body. Obesity predisposes the affected individuals to many disorders, such as non-insulin-dependent diabetes, hypertension, stroke, and coronary artery disease. In obesity, adipose tissues have altered metabolic and endocrine functions that lead to an increased release of fatty acids, hormones, and pro-inflammatory molecules. Adipose tissue macrophages are believed to be a key source of pro-inflammatory cytokines including TNF-alpha, iNOS and IL-6 (Weisberg et al., J. Clin. Invest., 112:1796-808 (2003)). Recruitment of macrophages to the adipose tissue is likely mediated by MCP-1 produced by adipocytes (Christiansen T, et al., Int J Obes (Lond). 2005 January; 29(1): 146-50; Sartipy et al., Proc. Natl. Acad Sci. U.S.A., 100:7265-70 (2003)).
Elevated MCP-1 may induce adipocyte differentiation and insulin resistance, and contribute to pathologies associated with hyper-insulinemia and obesity. MCP-1 is over-expressed in plasma in obese mice compared to lean controls and white adipose is a major source. MCP-1 has also been shown to accelerate wound healing, and has a direct angiogenic effect on epithelial cells, and may play a direct role in the remodeling of adipose tissue in obesity. (Sartipy P, Loskutoff D J., Proc. Natl. Acad. Sci. U.S.A., 100:7265 (2003)).
MCP-1 plasma levels are substantially increased in Diet Induce Obesity (DIO) mice, and a strong correlation between plasma MCP-1 levels and body weight has been identified. Furthermore, elevation of MCP-1 induced by high fat diet causes changes in the CD11b positive monocyte population in DIO mice. (Takahashi K, et al., J. Biol. Chem., 46654 (2003)).
Furthermore, chronic inflammation in fat is thought to play a crucial role in the development of obesity-related insulin resistance (Xu H. et al., J Clin Invest. 2003 December; 112(12):1821-30). It has been proposed that obesity related insulin resistance is, at least in part, a chronic inflammatory disease initiated in adipose tissue. Many inflammation and macrophage specific genes are dramatically upregulated in white adipose tissue in mouse models of genetic and high fat diet-induced obesity (DIO), and this upregulation precedes a dramatic increase in circulating insulin.
Increased expression levels of monocyte CCR2 and monocyte chemoattractant protein-1 in patients with diabetes mellitus (Biochemical and Biophysical Research Communications, 344(3):780-5 (2006)) were found in a study involving diabetic patients. Serum MCP-1 concentrations and surface expression of CCR2 on monocytes in diabetic patients were significantly higher than in non-diabetics, and the serum MCP-1 levels correlated with HbA1c, triglycerides, BMI, hs-CRP. Surface expression levels of CD36 and CD68 on monocytes were significantly increased in diabetic patients and more unregulated by MCP-1 in diabetics, augmenting uptake of ox-LDL, and hence potentially foam cell transformation. Elevated serum MCP-1 and increased monocyte CCR2. CD36. CD68 expression correlated with poor blood glucose control and potentially correlate with increased vessel wall monocyte recruitment.
MCP-1 is a potential player in negative cross talk between adipose tissue and skeletal muscle (Bianco J J, et al., Endocrinology, 2458 (2006)). MCP-1 can significantly reduce insulin-stimulated glucose uptake, and is a prominent inducer of insulin resistance in human skeletal muscle cell. Adipose tissue is a major secretory and endocrine active organ producing bioactive proteins regulating energy metabolism and insulin sensitivity.
CCR2 modulates inflammatory and metabolic effects of high-fat feeding (Weisberg S P, et al., J. Clin. Invest., 115 (2006)). Genetic deficiency in CCR2 reduced food intake and attenuated the development of obesity in mice fed a high fat diet. In obese mice matched for adiposity, CCR2 deficiency reduced macrophage content and inflammatory profile of adipose tissue, increased adiponectin expression, and improved glucose homeostatis and insulin sensitivity. In lean animals, no effect of CCR2 genotype on metabolic trait was found. In high-fat diet mice, CCR2 genotype modulated feeding, the development of obesity and adipose tissue inflammation. Once established, short term antagonism was shown to attenuate macrophage accumulation in adipose tissue and insulin resistance.
Chemokine and chemokine receptors are the key regulators of immune cell trafficking. MCP-1 is a potent chemoattractant of monocytes and T cells; its expression is induced under inflammatory conditions including proinflammatory cytokine stimulations and hypoxia. The interaction between MCP-1 and CCR2 mediates migration of monocytes, macrophage as well as activated T cells and play a key role in the pathogenesis of many inflammatory diseases. Inhibition of CCR2 functions using small molecule antagonists described in this invention represents a new approach for the treatments of inflammatory disorders.
Psoriasis is a chronic inflammatory disease characterized by hyperproliferation of keratinocytes and pronounced leukocyte infiltration. It is known that keratinocytes from psoriasis lesion express abundant CCR2 ligand MCP-1, particularly when stimulated by proinflammatory cytokines such as TNF-α (Vestergaard et al., Acta. Derm. Venereol., 84(5):353-8 (2004); Gillitzer et al., J. Invest. Dermatol., 101(2):127-31 (1993); Deleuran et al., J. Dermatol. Sci., 13(3):228-36 (1996)). Since MCP-1 can attract migration of both macrophages and dendritic cells expressing CCR2 to the skin, this receptor and ligand pair is believed to be important in regulating the interaction between proliferating keratinocytes and dermal macrophage during the development of psoriasis. A small molecule antagonist may thus be useful in the treatment of psoriasis.
In addition to inflammatory diseases, chemokines and chemokine receptors have also been implicated in cancers (Broek et al., Br. J. Cancer. 88(6):855-62 (2003)). Tumor cells stimulate the formation of stroma that secretes various mediators pivotal for tumor growth, including growth factors, cytokines, and proteases. It is known that the level of MCP-1 is associated significantly with tumor-associated macrophage accumulation, and prognostic analysis reveals that high expression of MCP-1 is a significant indicator of early relapse in breast cancer (Ueno et al., Clin. Cancer Res., 6(8):3282-9 (2001)). A small molecule antagonist of a chemokine may thus be able to reduce the release of growth-stimulating cytokines by blocking accumulation of macrophages at sites of tumor formation.
CCR2 and its ligand CCL2 also play a major role in conditioning the tumor microenvironment, and regulating the influx of both beneficial and deleterious immune cell populations to the tumor. As such recent clinical and pre-clinical literature has demonstrated a role for CCR2 in a variety of solid tumors either through up-regulation of its expression in transformed cells or in enhanced chemotaxis of inflammatory monocytes into the tumour that terminally differentiates into myeloid-derived suppressor cells (MDSCs) or tumour associated macrophages (TAMs). MDSCs/TAMs are thought to promote tumorgenesis through the following mechanisms: (1) contribute to the general immunosuppressive microenvironment, thereby promoting tumour growth, that abolish the cytotoxic functionality of infiltrating cytotoxic T cells (Mitchem et al, Cancer Res 73(3): 1128-1141), (2) enhance angiogenesis through secretion of vascular endothelial growth factor (VEGF) and other growth factors (Murdoch et al, Nat Rev Cancer 8: 618-631), (3) prevent tumour senescence (Di Mitri et al. AOP. Nature, 2014), and (4) promote tumour metastases into distal organs (Qian et al. Nature 475: 222-227). Thus, a small molecule antagonist can be useful in limiting tumorgenesis, enhancing tumour specific immune activity, and tumour metastases.
Provided herein are compounds that are CCR2 modulators and address some of the shortcomings identified with earlier CCR2 modulators.